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Marine Ecology Progress Series

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MEPS 529:35-48 (2015)  -  DOI: https://doi.org/10.3354/meps11324

More than passive drifters: a stochastic dynamic model for the movement of Antarctic krill

Kate Richerson1,2,*, George M. Watters3, Jarrod A. Santora2, Isaac D. Schroeder4,5, Marc Mangel2,6

1Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA 95064, USA
2Center for Stock Assessment Research, Department of Applied Mathematics and Statistics, University of California Santa Cruz, Santa Cruz, CA 95064, USA
3Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, NOAA Fisheries, La Jolla, CA 92037, USA
4Division of Physical and Biological Sciences, University of California at Santa Cruz, Santa Cruz, CA, 95064, USA
5Environmental Research Division, Southwest Fisheries Science Center, NOAA Fisheries, Pacific Grove, CA, 93950, USA
6Department of Biology, University of Bergen, Bergen 9020, Norway
*Corresponding author:

ABSTRACT: Antarctic krill Euphausia superba are a key part of the marine food web and are the target of the largest fishery in the Southern Ocean. Although ecosystem and management models typically assume that krill are passive drifters, their relatively large size and strong swimming ability suggest that the active movement of krill may play an important role in their spatial distribution. Thus, active swimming behavior by krill may influence spatial structure of food web interactions (e.g. feeding behavior of seabirds and marine mammals) and regional commercial fishery activity. The objective of this work was to model the potential for active movement to affect krill distribution, and consequently growth, reproductive success, and survival. We used state-dependent life history theory, implemented by stochastic dynamic programming, in combination with spatial information on food availability, current velocity, temperature, and predation risk, to predict krill swimming behavior near the northern Antarctic Peninsula. We found that including active krill behavior resulted in distribution patterns that are associated with increased survival, growth, and reproductive success compared to a model that treats krill as passive drifters. The expected reproductive success of actively behaving krill was about 70% greater than that of passively diffusing krill, suggesting that there are strong selective pressures for active behavior along oceanic drift trajectories. This modeling framework will benefit assessments of new catch limits as krill fishing grounds are partitioned into smaller spatial management units.


KEY WORDS: Euphausia superba · Behavior · Stochastic dynamic programming · Management · Advection · Southern Ocean


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Cite this article as: Richerson K, Watters GM, Santora JA, Schroeder ID, Mangel M (2015) More than passive drifters: a stochastic dynamic model for the movement of Antarctic krill. Mar Ecol Prog Ser 529:35-48. https://doi.org/10.3354/meps11324

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